The present invention relates to machines for manufacturing concrete blocks, and more particularly to a novel method and apparatus for forming blocks and pavers by ensuring that they are formed with a uniformly compacted density.
In the production of concrete blocks and pavers, it is conventional to use large block forming machines which vibrate and compress concrete material dispensed into a mold. After compression, the concrete blocks or pavers are stripped from the mold and taken to a suitable curing station, after which time the product is shipped.
One type of concrete block forming device is disclosed in Davies (U.S. Pat. No. 3,343,239). There, a mold box is supported above a pallet holder, suitably mounted in a frame structure, and a single vibrator rod is mounted on opposite sides of the mold box and connected thereto for imparting vibration to the mold box. The vibrator rods are connected adjacent their lower ends to a rotatable shaft which imparts vibration to the vibrator rods for vibrating the mold box. Vibration is used in an attempt to evenly distribute concrete material within the mold box.
Other examples of various types of vibrating apparatus for forming concrete blocks are disclosed in Sekiguchi (U.S. Pat. No. 4,193,754), Kitahara (U.S. Pat. No. 4,111,627), Gelbman (U.S. Pat. No. 3,659,986) and Hirt, et al. (U.S. Pat. No. 3,712,785). Each of these patents discloses some type of device for vibrating a mold or concrete product to effectuate a uniform mold fill. Additionally, there are systems which utilize rotatable vibrators connected to a pallet table, such as systems using electric vibrators (motors with eccentric weights built into them) usually in pairs which run in counter-opposing directions.